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Diffstat (limited to 'src/mcron/scripts/crontab.scm')
| -rw-r--r-- | src/mcron/scripts/crontab.scm | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/src/mcron/scripts/crontab.scm b/src/mcron/scripts/crontab.scm new file mode 100644 index 0000000..502fec6 --- /dev/null +++ b/src/mcron/scripts/crontab.scm @@ -0,0 +1,225 @@ +;;;; crontab -- edit user's cron tabs +;;; Copyright © 2003, 2004 Dale Mellor <dale_mellor@users.sourceforge.net> +;;; Copyright © 2016 Mathieu Lirzin <mthl@gnu.org> +;;; +;;; This file is part of GNU Mcron. +;;; +;;; GNU Mcron is free software: you can redistribute it and/or modify +;;; it under the terms of the GNU General Public License as published by +;;; the Free Software Foundation, either version 3 of the License, or +;;; (at your option) any later version. +;;; +;;; GNU Mcron is distributed in the hope that it will be useful, +;;; but WITHOUT ANY WARRANTY; without even the implied warranty of +;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +;;; GNU General Public License for more details. +;;; +;;; You should have received a copy of the GNU General Public License +;;; along with GNU Mcron. If not, see <http://www.gnu.org/licenses/>. + +(define-module (mcron scripts crontab) + #:use-module (ice-9 rdelim) + #:use-module (mcron config) + #:use-module (mcron utils) + #:use-module (mcron vixie-specification) + #:export (main)) + +(define* (show-help) + (display "Usage: crontab [-u user] file + crontab [-u user] { -e | -l | -r } + (default operation is replace, per 1003.2) + -e (edit user's crontab) + -l (list user's crontab) + -r (delete user's crontab") + (newline) + (show-package-information)) + +(define %options + '((user (single-char #\u) (value #t)) + (edit (single-char #\e) (value #f)) + (list (single-char #\l) (value #f)) + (remove (single-char #\r) (value #f)) + (version (single-char #\v) (value #f)) + (help (single-char #\h) (value #f)))) + + +;;; +;;; Entry point. +;;; + +(define* (main #:optional (args (command-line))) + (let ((opts (parse-args args %options))) + (when config-debug + (debug-enable 'backtrace)) + (cond ((option-ref opts 'help #f) + (show-help) + (exit 0)) + ((option-ref opts 'version #f) + (show-version "crontab") + (exit 0))) + (let ((hit-server + (λ (user-name) + ;; Procedure to communicate with running cron daemon that a user + ;; has modified his crontab. The user name is written to the + ;; /var/cron/socket UNIX socket. + (catch #t + (λ () + (let ((socket (socket AF_UNIX SOCK_STREAM 0))) + (connect socket AF_UNIX config-socket-file) + (display user-name socket) + (close socket))) + (λ (key . args) + (display "Warning: a cron daemon is not running.\n"))))) + + ;; Procedure to scan a file containing one user name per line (such + ;; as /var/cron/allow and /var/cron/deny), and determine if the + ;; given name is in there. The procedure returns #t, #f, or '() if + ;; the file does not exist. + (in-access-file? + (λ (file name) + (catch #t + (λ () + (with-input-from-file file + (λ () + (let loop ((input (read-line))) + (if (eof-object? input) + #f + (if (string=? input name) + #t + (loop (read-line)))))))) + (λ (key . args) '())))) + + ;; This program should have been installed SUID root. Here we get + ;; the passwd entry for the real user who is running this program. + (crontab-real-user (passwd:name (getpw (getuid))))) + + ;; If the real user is not allowed to use crontab due to the + ;; /var/cron/allow and/or /var/cron/deny files, bomb out now. + (if (or (eq? (in-access-file? config-allow-file crontab-real-user) #f) + (eq? (in-access-file? config-deny-file crontab-real-user) #t)) + (mcron-error 6 "Access denied by system operator.")) + + ;; Check that no more than one of the mutually exclusive options are + ;; being used. + (when (> (+ (if (option-ref opts 'edit #f) 1 0) + (if (option-ref opts 'list #f) 1 0) + (if (option-ref opts 'remove #f) 1 0)) + 1) + (mcron-error 7 "Only one of options -e, -l or -r can be used.")) + + ;; Check that a non-root user is trying to read someone else's files. + (when (and (not (zero? (getuid))) + (option-ref opts 'user #f)) + (mcron-error 8 "Only root can use the -u option.")) + + (letrec* (;; Iff the --user option is given, the crontab-user may be + ;; different from the real user. + (crontab-user (option-ref opts 'user crontab-real-user)) + ;; So now we know which crontab file we will be manipulating. + (crontab-file (string-append config-spool-dir "/" crontab-user)) + ;; Display the prompt and wait for user to type his + ;; choice. Return #t if the answer begins with 'y' or 'Y', + ;; return #f if it begins with 'n' or 'N', otherwise ask + ;; again. + (get-yes-no (λ (prompt . re-prompt) + (if (not (null? re-prompt)) + (display "Please answer y or n.\n")) + (display (string-append prompt " ")) + (let ((r (read-line))) + (if (not (string-null? r)) + (case (string-ref r 0) + ((#\y #\Y) #t) + ((#\n #\N) #f) + (else (get-yes-no prompt #t))) + (get-yes-no prompt #t)))))) + ;; There are four possible sub-personalities to the crontab + ;; personality: list, remove, edit and replace (when the user uses no + ;; options but supplies file names on the command line). + (cond + ;; In the list personality, we simply open the crontab and copy it + ;; character-by-character to the standard output. If anything goes + ;; wrong, it can only mean that this user does not have a crontab + ;; file. + ((option-ref opts 'list #f) + (catch #t + (λ () + (with-input-from-file crontab-file + (λ () + (do ((input (read-char) (read-char))) + ((eof-object? input)) + (display input))))) + (λ (key . args) + (display (string-append "No crontab for " + crontab-user + " exists.\n"))))) + + ;; In the edit personality, we determine the name of a temporary file + ;; and an editor command, copy an existing crontab file (if it is + ;; there) to the temporary file, making sure the ownership is set so + ;; the real user can edit it; once the editor returns we try to read + ;; the file to check that it is parseable (but do nothing more with + ;; the configuration), and if it is okay (this program is still + ;; running!) we move the temporary file to the real crontab, wake the + ;; cron daemon up, and remove the temporary file. If the parse fails, + ;; we give user a choice of editing the file again or quitting the + ;; program and losing all changes made. + ((option-ref opts 'edit #f) + (let ((temp-file (string-append config-tmp-dir + "/crontab." + (number->string (getpid))))) + (catch #t + (λ () (copy-file crontab-file temp-file)) + (λ (key . args) (with-output-to-file temp-file noop))) + (chown temp-file (getuid) (getgid)) + (let retry () + (system (string-append + (or (getenv "VISUAL") (getenv "EDITOR") "vi") + " " + temp-file)) + (catch 'mcron-error + (λ () (read-vixie-file temp-file)) + (λ (key exit-code . msg) + (apply mcron-error 0 msg) + (if (get-yes-no "Edit again?") + (retry) + (begin + (mcron-error 0 "Crontab not changed") + (primitive-exit 0)))))) + (copy-file temp-file crontab-file) + (delete-file temp-file) + (hit-server crontab-user))) + + ;; In the remove personality we simply make an effort to delete the + ;; crontab and wake the daemon. No worries if this fails. + ((option-ref opts 'remove #f) + (catch #t + (λ () + (delete-file crontab-file) + (hit-server crontab-user)) + noop)) + + ;; XXX: This comment is wrong. + ;; In the case of the replace personality we loop over all the + ;; arguments on the command line, and for each one parse the file to + ;; make sure it is parseable (but subsequently ignore the + ;; configuration), and all being well we copy it to the crontab + ;; location; we deal with the standard input in the same way but + ;; different. :-) In either case the server is woken so that it will + ;; read the newly installed crontab. + ((not (null? (option-ref opts '() '()))) + (let ((input-file (car (option-ref opts '() '())))) + (catch-mcron-error + (if (string=? input-file "-") + (let ((input-string (read-string))) + (read-vixie-port (open-input-string input-string)) + (with-output-to-file crontab-file + (λ () (display input-string)))) + (begin + (read-vixie-file input-file) + (copy-file input-file crontab-file)))) + (hit-server crontab-user))) + + ;; The user is being silly. The message here is identical to the one + ;; Vixie cron used to put out, for total compatibility. + (else (mcron-error 15 + "usage error: file name must be specified for replace."))))))) |